Pollution and health risk assessment of potentially toxic elements in soil-crop systems near a pyrite mining area, China.

Abstract

Mining activities have increasingly contributed to soil contamination by potentially toxic elements (PTEs), which pose significant environmental and health risks, especially in historically under-regulated regions. This study investigated PTE contamination and associated risks in Longyou, a typical pyrite mining area in southeastern China. A total of 42 site-matched soil and crop samples were collected for the analysis of PTE total content and chemical fractions. The pollution levels and potential risks were assessed using the geo-accumulation index (I_geo), enrichment factor (EF), ecological risk index (RI), risk assessment code (RAC), and health risk models. The results revealed significant enrichment of Cd, Cu, Pb, and Zn in the soils, primarily due to sulfide mineral weathering and historical mining activities. Cd was identified as the predominant pollutant, with content of up to 46% in the bioavailable fraction, indicating its high mobility and potential for uptake by crops. Notably, 28.5% of rice samples exceeded the national safety limits for Cd, highlighting a critical dietary exposure pathway. The ecological risk assessments classified the risk from Cd as moderate to high. The health risk assessment showed that both the hazard index (THI) values (4.49 for adults and 10.40 for children) and carcinogenic risk (TCR) values (0.0025 for adults and 0.0014 for children) exceeded the acceptable thresholds, with children facing significantly higher risks than adults. Cd and As were the main contributors to both non-carcinogenic and carcinogenic risks, with rice consumption identified as the primary exposure pathway. These findings underscore the necessity of targeted risk mitigation and sustained monitoring to minimize long-term environmental and human health impacts in mining-affected regions.